Grid construction



July2 6,196O A. P. HAASE I 2,946,915

GRID CONSTRUCTION Filed July 21,, 1954 3' INVENTORI ALLEN P. HAASE I BY HIS TORNY GRID CONSTRUCTION Allen P. Haase, Owensboro, Ky., assignor to General Electric Company, acorporation of New York Filed July 21, 1954, Ser. No. 444,750

4 Claims. (Cl. 313-348) My invention relates to grid electrodes for use in electron discharge devices and more particularly to improved grid electrodes.

An object of my invention is to provide a grid struchim which alleviates many of the disadvantages associated with grids ofthe'wire wound types.

A further object of my invention is to provide new and improved mesh grids.

-A still further object of my invention is to provide a .novel mesh grid construction. having integral supporting portions and integral means for aiding in mounting the grid in an electron discharge device.

In the attainment of the foregoing objects, I provide a grid with an exceedingly high transmission factor while at the same time providing a grid which has an unusually high mechanical strength and which may be readily assembled in electron discharge devices.

. Further objects and advantages of my invention will become, apparent and the invention will be more clearly understood by reference to the accompanying drawing, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification. L In the drawing: i j V V Fig. 1 is an elevational view of an electroformed strip jof jcontiguously located grid sections;

atent 2,946,915 Patented July 26, 1960 ice 7 2 mesh area. Referring to Fig. In it may be see that solid support areas 3 are preferably considerably thicker than the mesh area. This feature of additional thickness gives added mechanical strength without reducing the transmission factor since the mesh thickness is held constant.

One method which has been developed for making grids of this type employs electroforming. This term is used herein to refer to the. method of making metal parts of a given design by making a drawing of the design, photographically reproducing it on a sensitized plate, developing the plate, and electrolytically depositing metal in accordance with the design appearing on the developed plate; To provide a support portion which is thicker than the mesh portion, the'mesh area is masked after the electrolytic depositing of metal has built up this area to the desired thickness and an additional plating application is performed until the piece in the unmasked areas is built up to the desired thickness. For example, I have effected a very sturdy mesh structure having a high transmission factor by making the thickness of the mesh area placeby a conventional lock seam 4. Other means for holding such a cylinder in place, such, for example, as by Welding, will be readily apparent to those skilled in e the art.

' with respect to a vertical support member 7 which in a Fig-1a is a transverse sectional view of a portion of Figs. 6 and 7, are fragmentary perspective views showing further embodiments of my invention.

In Fig. 1 there is illustrated a continuous strip 1 of grid structures fabricated by electroforming techniques and having mesh or perforate areas 2 disposed on opposite sides of imperforate support or solid areas 3, all of which areas are integrally formed. Portions of strip 1 of the type included between lines A and B are separable and can be formed into electrodes for use in electron discharge devices. Grids of this mesh type, when employed as control grids, may have a wide range of transmission factors that may extend as high as 60% to 80%, or higher while at the same time having an unusually high mechanical strength. The mesh area 2 itself provides good lateral support as compared with grids of the type wherein wires are arranged'in parallel relationship and supported only at the ends thereof, but I am able to further increase the strength of this grid by providing support portions which are constructed in tegrally with and having a greater (thickness than the completed electron discharge device would probably .be the cathode or cathode support member. Insulating spacers 8 and9 maybefastened to and supported by member 7 as well as by the gridstructures Sand 6';

7 These spacers are respectively provided with arcuate slots 10, 11,12,13', and 10, and 11, 12T, and13 through which are inserted portionsgrofthe supporting part of cylindrical grid electrodes 5;and.6; Such an arrangement of grid electrodes in an electron discharge device provides good lateral support and locationing for the grid area so that the microphonics problem generally associated with electron discharge devices is greatly diminished. In the completed device the anode would be coaxial with and surround said grids.

To assist in mounting electrodes of the mesh type herein described, it has been found advantageous to provide integral aligning and supporting members, such, for example, as extending portions 1 4 and 15 at opposite ends of the mesh areas 2. It will be readily understood that this is but one possible embodiment, and that such extensions or tabs of lesser or greater length and width could be provided at more or less frequent intervals as desired. Because these tabs are integrally formed with respect to the mesh area and other support areas, very accurate alignment of the mesh area. is facilitated, and furthermore, a good structural support is provided. When the electrodes are formed into a cylinder such as is illustrated in the electrode of Fig. 2, extensions 14 and 15 have a shape corresponding to part of the arcuate slots 10, 11, 12, 13, etc. in spacers 8 and 9. Extensions -14 and 15 are provided with chamfered or beveled corners 16 and 17 to facilitate insertion thereof into the slots or spacers 8 and 9.

In Fig. 4 there is illustrated another embodiment of my invention wherein an electroformed grid structure similar l :3 to that illustrated in Fig. lis formedjntheshape of a half grid. In this particular embodiment the mesh area 18 and the integral supporting member 19 are formed into a portion of. a half-hexagon. ilmvilli beiunderstoodithat other: shapes; such, for: example, .as -arcuates,.:=planes,' etc. could be utilized. The sides of: the supportareasylt) and 21 are ofaV-shaped cross-.sectionfdnadded strength, -:and extensions or tabs :22 and 23 are provided onropposite sides of the mesh area rather than opposite thetcenter thereof asv in the embodiment illustrated in-Figs. s1 :and 2.

I n Fig. 5 thereis showmanothenembodiment 'ofmy invention .wherein is provided ax-half grid 'for use in. an electron. discharge. device of' the remote cut-01f. type and, to that end, the .vertical spacing of the: grids 2-varied in accordance with any desired pattern. 'Thetransmission factor of the gridof-Fig-S increases toward the center. Such a gridhas the electrical characteristics of a variable pitch :wirewound type, hutsince it=is,1according to this invention, electroformed, the: special. gears and cams which are required towind the conventional variable pitch grids are eliminated. Furthermore, the mesh can readily'be designed. to have any distributiomof cut ofi characteristic that isidesire'd since thetransient response of winding equipment is not a factorin the fabrication of the part.

If it is desired to obtain a cylindrically shaped grid having. circular symmetry, the mesh will, of course, provide sufficient self-support, but it would generally be desirable to provide solid bands-at the-ends-of the cylinder for-greater ease in fabrication 0f the finaltube.

Referring to Figs. 6 and 7, there are illustrated other embodiments of my invention, whereinis made greater use of the available cathode area. In the grid of Fig. 6 a single vertical solid support-area-isemployed whereas in the grid of:Fig. 7 no such-support area is provided. Thus, in the embodiment of Fig. 7, cylindrical grids havinga rtransmittingarea extending throughout a full 360 degrees may be constructed in accordance with my invention. In both of these embodiments shown a lock seam is shown for purposes of illustration,-and it will be understood that other meansforholding the grid in a'cylinder form may be employed.

While certain specific' embodi-rnents havebeen shown and deseribed, it will, of course,be-understood that various modifications may bemade without departing from my invention.

Therefore, by the appended claims, I intend to cover all such changes and modificationswhich' fall within the truespirit and scopeof my invention.

What I claim as new. and desire toisecureflby Letters Patent of the United States is:

1. A self-supporting grid structure for use in an electron discharge device consisting of a single sheet of metal having an arcuate cross-section and including an integral perforate area constituting an electron permeable portion of said structure andan imperforate area limited to only the marginal. portion. of said.sheet and constituting a support portion of said structure, saidimperforate area including a "portion'that is channel-like inacross-section whereby said structure isrendered-more rigid, said perforate area of saidsheet being-ofgsubstantially lesser thickness than said imperforate area throughout the whole of said perforate area, .whereby said perforate area is adapted for maximizing electron transmission therethrough.

2. A self-supporting grid structure according to claim 1, wherein said-perforate area of-said sheet has a'thickness of less than .001 of an inch and saidiimperforate area of said sheet has a thickness of: between .006 to .0l'0 of; an inch.

3. A self-supportinggrid structure .accordingto: claim 1, wherein supporting tabs are'integral with said imperforate area and extend therefrom. Y w

4. A self-supporting grid structure according to claim 1, wherein the apertures defined by said perforate area vary in dimensions for varying the transmission factor'of said grid structure.

References Cited in: the file ofthisqpatent UNITED STATES PATENTS 1,537,708 SchOttky May 12, 1925 1,543,033 Smelling .Tune23, ,1925 1,722,468 Hunter "July 30,1929

7 1,844,319 Hatt Feb. 9,.1932 1,933,109 Hafecost Oct. 31,1933 2,115,855 Holman MayB, 1-938 2,185,590 Epstein Jan. 2,119.40 2,233,741 Kirsten Mar. 4, 19.41

2,246,380 Norris .]'une 17, 1941 2,261,154 Hansenet ..Nov. 4,.1941 2,443,119 Rubin Tune 18,1948 2,469,689 Gresham May 10,1949

FOREIGN PATENTS 302,418 Great Britain Dec. 20,1928 1,039,594 France Oct. 38,1953 

